Discounted This very solid black alloy 50mm long Tri-Rail mounts easily to barrels up to 1" diameter from .22 rifles to 12g shotguns. The other recess fits lights or lasers also up to 1” diameter. Or this can be used as a shotgun barrel and magazine extension clamp as pictured. Three 20.5mm wide Picatinny weaver rails provide the perfect platform for mounting accessories such as light, laser, bipod, grip etc. It also has a hole each side for a QD push button sling swivel (which I have listed separately). Allen key and a full set of extra long screws included. + SILVER available at an extra $10.